As a medical instrument equipped with a manipulation rope, for example, an endoscope treatment instrument disclosed in JPH8-126648 is known. In the endoscope treatment instrument, an operation unit being held by hand and a treatment unit provided at its leading end are connected by a manipulation wire rope having torque transmittability. An operator inserts the treatment unit into a body cavity of a patient and operates the operation unit, whereby an operating force thereof is transmitted to the treatment unit by the manipulation wire rope. The manipulation wire rope allows a pushing force, a pulling force, and a rotational force (torque) to be transmitted from the operation unit to the treatment unit. By the transmitted force, a portion, of a body, to be treated can be subjected to medical treatment.
The manipulation wire rope is required to have not only transmittability of pushing and pulling force, but also an excellent torque transmittability (rotation followability) according to application of the manipulation wire rope. In a case where a torque transmittability or the like of the manipulation wire rope is insufficient, an operation of the operation unit is not reproduced by the treatment unit. Furthermore, particularly in the field of medical devices, the manipulation wire rope is required to have flexibility according to the diameter of the medical device being reduced.
A manipulation wire rope used for a medical treatment instrument is disclosed in JP2005-13296. The wire rope is structured such that, by, for example, wires in the outer layer and wires in the inner layer being stranded in a parallel lay, the wires adjacent to each other are brought into contact with each other as closely as possible along the rope longitudinal direction. This structure is adopted in order to inhibit reduction of an operating force and an operation amount from an operation unit to a treatment unit. However, in the field of medical devices, torque transmittability, flexibility, and the like of the manipulation wire rope are required to be further improved.